假设你在sqldf
使用read.csv.sql
与默认sqlite
数据库它是生产对于C的因子列,以便
(1)刚转换的值使用as.numeric(as.character(...))
像这样的数字:
> Lines <- "A,B,C
+ 3,4,
+ 2,4,6
+ 34,23,43
+ 2,5,
+ "
> cat(Lines, file = "stest.csv")
> library(sqldf)
> DF <- read.csv.sql("stest.csv")
> str(DF)
'data.frame': 4 obs. of 3 variables:
$ A: int 3 2 34 2
$ B: int 4 4 23 5
$ C: Factor w/ 3 levels "","43","6": 1 3 2 1
> DF$C <- as.numeric(as.character(DF$C))
> str(DF)
'data.frame': 4 obs. of 3 variables:
$ A: int 3 2 34 2
$ B: int 4 4 23 5
$ C: num NA 6 43 NA
(2),或者如果我们使用sqldf(..., method = "raw")
那么我们可以只使用as.numeric
:
> DF <- read.csv.sql("stest.csv", method = "raw")
> str(DF)
'data.frame': 4 obs. of 3 variables:
$ A: int 3 2 34 2
$ B: int 4 4 23 5
$ C: chr "" "6" "43" ""
> DF$C <- as.numeric(DF$C)
> str(DF)
'data.frame': 4 obs. of 3 variables:
$ A: int 3 2 34 2
$ B: int 4 4 23 5
$ C: num NA 6 43 NA
(3)如果可行的话您使用read.csv
那么我们确实得到NA
填补权:
> str(read.csv("stest.csv"))
'data.frame': 4 obs. of 3 variables:
$ A: int 3 2 34 2
$ B: int 4 4 23 5
$ C: int NA 6 43 NA